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Cambio de espín inducido por la luz por ligandos externos fotodissociables: un nuevo principio para la conmutación
Steffen Thies1, Hanno Sell, Christian Schütt
1Otto-Diels-Institut für Organische Chemie, Christian-Albrechts-Universität, Otto-Hahn-Platz 4, D-24098 Kiel, Germany.
Journal of the American Chemical Society
|September 6, 2011
Resumen
Los investigadores lograron la conmutación magnética a temperatura ambiente en moléculas individuales utilizando la luz. Esta conmutación de estado de giro inducida por coordinación impulsada por la luz (LD-CISSS) ofrece nuevas posibilidades para el magnetismo molecular.
Área de la Ciencia:
- El magnetismo molecular es el magnetismo molecular.
- Química supramolecular de las moléculas.
- La fotoquímica es la fotoquímica.
Sus antecedentes:
- La bistabilidad magnética en los materiales de cruce de espín es típicamente un fenómeno de estado sólido colectivo.
- Lograr la conmutación magnética a nivel molecular en solución presenta un desafío significativo.
Objetivo del estudio:
- Para demostrar la conmutación magnética impulsada por la luz de moléculas individuales en una solución homogénea.
- Investigar el mecanismo de la conmutación de estado de giro inducida por coordinación impulsada por la luz (LD-CISSS) a nivel molecular.
Principales métodos:
- Utilizó Ni-porfirina como una plataforma cuadrada plana y azopiridinas como ligandos axiales fotodissociables.
- Utilizó luz UV (365 nm) y luz visible (455 nm) para inducir la isomerización trans-cis de las azopiridinas, alterando la coordinación y el estado de espín.
- Se determinaron las constantes de asociación para los complejos de porfirina/azopiridina y se evaluó el efecto del tamaño del sustituto en la eficiencia de la conmutación.
Principales resultados:
- Se ha demostrado el cambio reversible entre los estados diamagnéticos (bajo espín, S=0) y paramagnéticos (alto espín, S=1) para los complejos de Ni-porfirina en solución.
- Se logró una conmutación fotoinducida y reversible de 20-68% de especies paramagnéticas de Ni a temperatura ambiente utilizando azopiridinas sustituidas por isopropilo.
- Se demostró que los sustituyentes más grandes en las azopiridinas mejoran la diferencia en las constantes de unión entre los isómeros, mejorando la eficiencia de conmutación.
Conclusiones:
- Las moléculas individuales en solución pueden exhibir bistabilidad magnética impulsada por la luz.
- LD-CISSS proporciona una nueva vía para controlar las propiedades magnéticas moleculares utilizando la luz.
- El sistema ofrece potencial para el desarrollo de nuevos interruptores moleculares y dispositivos de memoria.
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